Add missing variable in templates regarding toc (#127)

Related to #123 and alignement with `html_document()` behavior
diff --git a/DESCRIPTION b/DESCRIPTION
index 797f81c..b780b5a 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -33,8 +33,11 @@
 Imports:
     rmarkdown (>= 1.7)
 Suggests:
+    xfun (>= 0.21),
+    xml2,
     bslib,
-    testthat (>= 3.0.0)
+    testthat (>= 3.0.0),
+    withr (>= 2.4.2)
 Encoding: UTF-8
 Roxygen: list(markdown = TRUE)
 RoxygenNote: 7.1.2